The use of ultraviolet or UV-absorption for analyzing the contents of a petroleum distillate are well known. A method of testing and treating stored fuel was described in Kitchen, III et al, U.S. Pat. No. 4,556,326 issued Dec. 3, 1985. While it is not explicitly set forth that this testing method was to determine gum content in a distillate fuel, it would appear that gum content was at least a major concern. The analytical method utilizes UV absorption. A sample is acquired from a fuel tank and is heated to a high enough temperature below the boiling point of the fuel to accelerate the formation of macroscopic agglomerates by rapid polymerization of agglomerating agents. UV transmission characteristics of the fuel sample are acquired before heating, after heating and after cooling. The transmission characteristics are determined at a single wave length or a single narrow band of wave lengths between 400 and 680 nanometers. The most preferred single wave length is at 572 nanometers. In the quality control of a gasoline range distillate hydrocarbon, this type of testing procedure is not viable. In addition, it has been discovered, as shown in the instant drawings, that total absorption at 572 nanometers is not viable to determine gum content of a gasoline range distillate hydrocarbon. This test is also not viable as an on-line analytic test method for determining gum content in a gasoline boiling range hydrocarbon. In contrast, the instant invention is very simple yet accurate. It does not require testing of a preheated sample, a heated sample and then a cooled sample in order to adequately determine gum content.
Two ultraviolet analyzers for determining the content of butadiene in a hydrocarbon are disclosed in U.S. Pat. No. 2,847,578 issued Aug. 12, 1958 and U.S. Pat. No. 2,822,475 issued Feb. 4, 1958. The teachings of these analyzers are herein incorporated by reference as they relate to the ability of a UV analyzer to focus on a particular portion of a UV spectrum. Sparks,Jr., U.S. Pat. Nos. 2,900,510 and 2,905,823, also discloses analyzers for determining butadiene content. The disclosure of the analytical hardware tools of these two references is also incorporated by reference herein to this specification.
Slurry coker feedstock is analyzed in Sien et al, U.S. Pat. No. 4,388,408 issued June 14, 1983 to determine via UV absorptivity the suitability of the feedstock to produce electrode grade coke. This disclosure, like that of Kitchen et al, relies upon individual wavelengths and not on the integration or summation of a number of absorptions over a range of wavelengths. ASTM test methods D-2007 and D-2008 specify wavelengths characteristic of most polynuclear aromatics of between 280 and 400 millimicrons. Three specific wavelengths are noted. Tests 1 through 15 of Table 1 of the patent show representatives of these three peak heights. Finally, in Chew III, U.S. Pat. No. 4,149,805 issued Apr. 17, 1979, the amount of kerogen of an oil shale is taught as being proportional to the amount of light absorbed by the oil shale at a selected wavelength.